COEFFICIENTS OF FRICTION

Absolute surface roughness

0.0005 mm–0.0007 mm

The values of Hazen-Williams coefficient

The values of the head losses in the charts were calculated using the Hazen-Williams formula with Hazen-Williams coefficient C= 155

Manning coefficient:

n= 0.005 – 0.007

Reduction factors for higher temperatures

The values of the head losses J in the charts are correct for 20°C. At higher temperature the head losses are lower.

For different temperatures, multiply the value of J by the following reduction factors:

10°C – 1.03
20°C – 1.00
30°C – 0.98
40°C – 0.93
50°C – 0.91
60°C – 0.88
70°C – 0.85
80°C – 0.83
90°C – 0.81

Calculating Pexgol pipes for boreholes

Pexgol pipes can be used as riser pipes for boreholes. For energy-saving reasons, we recommend choosing a Pexgol pipe with head losses that do not exceed J=5%, and preferably lower. However, please note that designing these pipes is complicated, due to the complex three dimensional stress regime in these applications.

Pexgol’s Technical Department will calculate the pipe design for you after receiving the completed borehole questionnaire.

We are ready to provide you with a quote for your project.

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